Tuesday, 13 May 2008

:: Description of new material of the aetosaur Desmatosuchus spurensis (Archosauria: Suchia) from the Chinle Formation of Arizona and a revision of the genus DesmatosuchusWilliam Parker, PaleoBios 28(1):1–40, May 12, 2008Abstract: A new specimen of Desmatosuchus from northeastern Arizona (MNA V9300) preserves almost the entire vertebral column, the pelvis, and the majority of the armor carapace, allowing for an unprecedented detailed description of the taxon.

Articulation and reconstruction of the armor carapace demonstrates that previous reconstructions of Desmatosuchus are erroneous in the orientation and position of the lateral armor. Lateral plates of the anterior dorsal region possess low rounded knobs instead of developed spines.

The dorsal flange of the lateral plates of the dorsal region is longer than the lateral or ventral flange making the carapace transversely wider than previously thought. As a result, previous reconstructions articulate the lateral armor not only backwards but also on the wrong sides of the body. Posterior presacral vertebrae are extremely robust and possess fused ribs and the last presacral vertebra has been fused to the sacrum, a character that may be taxonomically useful.

A prefrontal bone is also present in Desmatosuchus, contrary to previous descriptions. Reinvestigation of the genus Desmatosuchus suggests that there are only two valid species, D. spurensis and D. smalli. The lectotype of Episcoposaurus haplocerus is referable to Desmatosuchus but indeterminate at the species level, and therefore represents a nomen dubium.

Accordingly, D. spurensis is reinstated as the type species of Desmatosuchus and the new Arizona specimen is assigned to this taxon. Acaenasuchus geoffreyi, a purported juvenile form of Desmatosuchus, is not referable to Desmatosuchus.

PALEONTOLOGICAL GEMS

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FOUR RAINDROPS...

Four individual raindrops falling on the high peaks of the Rockies could easily end up thousands of miles apart -- one flowing north to the Beaufort Sea, another reaching the the Gulf of Mexico, a third would be absorbed into Hudson Bay to the east and the last into the vast Pacific.

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WEST COAST

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KITSILANO KANE

GODS OF THE SEA

Ammonites were a group of hugely successful aquatic molluscs that looked like the still extant Nautilus, a coiled shellfish that lives off the southern coast of Asia. While the Nautilus lived on, ammonites graced our waters from around 400 million years ago until the end of the Cretaceous, 65 million years.

COHO FISHING | SEYMOUR INLET

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EQUUS FERUS CABALLUS

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CUDDLY CUTIE PIES

Building British Columbia

Some 270 million plus years ago, had one wanted to buy waterfront property in what is now British Columbia, you’d be looking somewhere between Prince George and the Alberta border.

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FOSSILHUNTRESS TRACKS

HEIDI, DANIEL & CHARLES HELM

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SUNSHINE COAST

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MYOMANCY | MICE PREDICTOR

Myomancy was a method of divination by mice. Their behaviour was observed and taken as a omen of what was to come. Modern scientists study the movements of mice more than the ancient myomancers did and for ends that are not dissimilar.

SISTERS | NIGHT AND DAY

ALPINE ADVENTURE

Heidi Henderson | Fossil Huntress

DIATRYMA TRACKWAY

Rare bird, reptile and mammal tracks have been immortalized in the outcrops of the Chuckanut Formation. Diatryma tracks have also been found there. These massive flightless birds reached up to 9 feet in height and made a living in the grasslands and swamps of the Eocene.

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TROPICAL CHUCKANUT

The siltstones, sandstones, mudstones and conglomerates of the Chuckanut Formation were laid down about 40-54 million years ago during the Eocene epoch, a time of luxuriant plant growth in the subtropical flood plain that covered much of the Pacific Northwest.

PALEONTOLOGICAL EXPLORER

TUMBLER RIDGE TRACKWAY

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OLYMPIC PENINSULA

One of the most beautiful drives in the Pacific Northwest is the coastline along the Olympic Peninsula from Port Angeles to Neah Bay. This stretch of road meanders alongside the Clallam Formation, a thick, mainly marine sequence of sandstones and siltstones that line the northwestern margin of the Olympic Peninsula, western Washington.

DINOSAUR TRACK

oregon paleontology

The Farallon Plate took a turn north some 57 million years ago, sweeping much of western coastal Oregon along with it. By the middle Oligocene, the Cascadia Subduction Zone was in full force with growing pressure erupting volcanoes along the Western Cascades, a pattern that was to continue well into the Miocene. The soft ocean sediments of Oregon contain beautifully preserved gastropods, bivalves and cephalopods.

BLESS GOOD FRIENDS

rain or shine

Rain long foretold takes a long time to pass; if it arrives on short notice, it soon will pass. For the folks I go out collecting with all hikes, digs and kayak trips are rain or shine. Safety is always top of mind and prepping for the weather is paramount. Keep yourself safe whatever part of the world you choose to explore. For forecasts of marine weather in Vancouver call 604.666.3655 or visit http://www.weatheroffice.com/

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ARTWORK BY TINA BEARD

Tina Beard is an artist and paleo enthusiast on Vancouver Island. She does some of the most exquisite artwork I've had the pleasure to behold.